The activities of the Mechanical Assembly Unit, TU 18.104.22.168, are summarized in this report. This group prepared the experimental nuclear weapons and delivered them to a predetermined zero point, which was the focal point for all the instrumentation involved in Operation Greenhouse. The Rear Area portion of this report is essentially concerned with group organization, supply, and training. The Forward Area operations discuss the actual assembly work aboard the laboratory ship, USS Curtiss (AV-4), the weapon delivery to the zero towers, and final positioning and assembly in the tower cabs. The report includes, in Sec. 3.3.2 and Appendix A, bomb assembly and delivery schedules and sample check sheets comprising a weapons technical inspection data book (also known as 'bomb book') and a shipping manifest listing tools, equipment, and supplies.